Patent GB-717265-A (GB)
Title: Tetrahydrofurfuryl esters of polychlorophenoxy acetic acids as herbicidal agents
IPC: A01N39/04
Filed: 1952-03-26
Abstract: The invention comprises the tetrahydrofurfuryl esters of 2,4-dichloro- and 2,4,5-trichloro-phenoxy acetic acid.  They may be made by the condensation of the acid and alcohol in the presence of a dehydrating esterification agent such as phosphoric or p-toluenesulphonic acid.  Advantageously a slight excess of alcohol is used and the reaction effected in a water-immiscible solvent. Desirably weakly acidic esterification agents are used. The esters are used in herbicidal compositions (see Group VI) and a technical grade of tetrahydrofurfuryl alcohol may be used containing pentanediols.ALSO:The invention comprises compositions for use in the control of vegetation growth containing as active components tetrahydrofurfuryl esters of polychlorophenoxy-acetic acids. Esters of 2, 4-dichlor- and 2, 4, 5-trichloro-phenoxyacetic acid are particularly mentioned.  The esters may be used in dust or liquid spray compositions, diluents specified being talc, soapstone, frianite, pyrophyllite, Attapulgus clay, chalk or volcanic ash. Preferably water-soluble and/or oil-soluble emulsifying or wetting agents are also present.  The dusting compositions may be further diluted with dusts before use or compounded as wettable powders which are diluted to form stable emulsions with water or mineral oil.  The esters are most active in the form of liquid sprays.  The surface-active agents may be of the ionic or non-ionic type or mixtures of both types may be used. Petroleum oils, e.g. Diesel oil, are preferred diluents, the esters being added thereto in concentrates in mutual solvents such as aliphatic esters and ketones, e.g. isopropyl acetate, methyl isopropyl ketone and cyclohexanone and aromatic compounds such as xylene, cresylic acids and methyl napthalenes.  Other plant hormones may be present, e.g. a mixture of 2, 4-dichlorophenoxyacetic acid and 2, 4, 5-trichlorophenoxyacetic acid and and insecticides and fertilizers may also be present.  In minute concentrations the esters stimulate plant growth and germination.  As phytocides they are used in concentrations at at least 0.04 per cent by weight of parent acid, generally 0.04-10 per cent when sprayed from field rigs and 1.5-4.0 per cent when sprayed from aeroplanes.  Concentrates in cresylic acid may be maintained liquid at 0 DEG F and may be diluted in petroleum oils. Cresols or xylenols enhance the phytocidal activity of the composition.  When cresylic acid is used a preferred emulsifying agent is an amine salt of a low molecular weight fatty acid, particularly those obtained by neutralizing fatty acids containing 1-3 carbon atoms with oil soluble, high molecular weight, aliphatic amines.  In examples a concentrate of the tetrahydrofurfuryl ester of 2, 4-dichlorophenoxyacetic acid in technical xylene with an alkyl benzyl trimethyl ammonium chloride and an alkyl aryl polyethylene glycol ether is diluted with Diesel oil and/or water to produce sprays, a concentrate of the tetrahydrofurfuryl ester of 2, 4, 5-trichlorophenoxyacetic acid in technical xylene with a sodium alkyl aryl sulphonate and an alkyl aryl polyethylene glycol ether is diluted with Diesel oil and water, a concentrate of the latter ester in commercial cresylic acid with glacial acetic acid, methyl isobutyl ketone and oil soluble fatty amines made from tallow is made and a concentrate containing a mixture of the esters together with technical xylene, an alkyl benzyl trimethyl ammonium chloride and an alkyl aryl polythylene glycol ether is also prepared and diluted with Diesel oil and water.